연사 소개

[ 6차 온라인 심포지엄 ]

박 진 형

부교수

성균관대학교

대한민국

E-Mail: Jin.park@skku.edu

약력

2016. 09 ~ 성균관대학교 글로벌바이오메이컬공학과 부교수

2013. 01 ~ 2016. 08 Philips, CA, USA Senior Engineer

2012. 01 ~ 2012. 08 University of Southern California Post-Doctoral Research Associate

2004. 01 ~ 2008. 07 SIEMENS Korea Principal Engineer

강의 제목

Ultrasonic Devices to Investigate Controllable Neuronal Modulations

강의 내용

Ultrasonic techniques for brain stimulations have been receiving lots of attention for their high potential neuromodulations. Because focused ultrasound stimulations can be non-invasively delivered into specific regions in the brain, these methods are expected to perform comparable performance with deep brain stimulation. However, the effects of ultrasound stimulations in modulating brain functionality are mostly mild. This could be because the stimulations activate both excitatory and inhibitory neurons. Ultra-low-intensity ultrasound is recently reported to activate solely astrocyte. Brain stimulation with ultra-low-intensity ultrasound has rarely been investigated due to the lack of a reliable device to measure small neuronal signal changes made by the ultra-low intensity range. We propose Ultrasonocoverslip, an ultrasound-transducer-integrated-glass-coverslip that determines the minimum intensity for brain cell activation. Brain cells can be cultured directly on Ultrasonocoverslip to simultaneously deliver uniform ultrasonic pressure to hundreds of cells with real-time monitoring of cellular responses using fluorescence microscopy and single-cell electrophysiology. The sensitivity for detecting small responses to ultra-low-intensity ultrasound can be improved by averaging simultaneously obtained responses. Acoustic absorbers can be placed under Ultrasonocoverslip, and stimuli distortions are substantially reduced to precisely deliver user-intended acoustic stimulations. With the proposed device, we discover the lowest acoustic threshold to induce reliable neuronal excitation releasing glutamate. Furthermore, mechanistic studies on the device show that the ultra-low-intensity ultrasound stimulation induces cell type-specific neuromodulation by activating astrocyte-mediated neuronal excitation without direct neuronal involvement. Bidirectional control of epileptiform activities can be induced by repetitive ultra-low-intensity transcranial-focused ultrasound stimulations in a rat model of drug-induced acute epilepsy. It is found that repeated transmission of elongated (40 s), ultra-low pressure (0.25 MPa) ultrasound can fully suppress epileptic activities in electro-encephalography and cerebral blood volume measurements, while the change in bursting intervals from 40 to 20 s worsens epileptic activities even with the same burst length. Furthermore, the suppression induced by 40 s long bursts is transformed to excitatory states by a subsequent transmission. Bidirectional modulation of epileptic seizures with repeated ultrasound stimulation is achieved by regulating the changes in glutamate and 𝜸-Aminobutyric acid levels, as confirmed by measurements of expressed c-Fos and GAD65 and multitemporal analysis of neurotransmitters in the interstitial fluid obtained via microdialysis.